I have a W810i and I hate it, I am about to change it to the K800i as I really don't think the W810i is very good at all. If you can get the K800i as it'll have all the Features of the K800i but set out in a better way. But that is just my Personal Opinion!!
I have mine for a month now and I love it!!! I wouls say buy one - just not sure how anyone will top this in a year's time when it is time for me to upgrade.